Conveyors for transporting materials may take on various forms depending upon the function being performed. Some conveyors operate to transport material horizontally, while others are oriented at an inclined angle to elevate the materials. Still other conveyors include a generally vertical span for lifting or lowering material between lower and upper elevations. Vertically oriented conveyors may include plural-spaced retaining members, such as buckets, for holding the material during vertical transport and a discharge arrangement for discharging the content of the buckets upon arrival at either the upper or lower elevation. Other vertical conveyors use plural rollers, or idlers, with dual endless belt conveyor systems. The rollers typically engage opposed edges of the first and second conveyor belts and may be either aligned along the direction of travel of the belts or arranged in a staggered array. The rollers may even be arranged at an inclined angle relative to the direction of travel of the conveyor belts to provide desired operating characteristics such as directing the bulk material toward the centerlines of the two moving belts. Examples of these types of conveyors can be found in U.S. Pat. Nos. 3,982,626; 4,195,724 and 4,585,118.
Various attempts have been made to improve belt tracking for dual endless conveyor belts such as in the use of interlocking belts which are complex in design and expensive to manufacture. An example of this type of conveyor can be found in U.S. Pat. No. 4,425,995. Even the use of spaced rollers engaging adjacent edge portions of the two transport belts has suffered from limitations in terms of bulk material becoming lodged between the edges in the space between adjacent rollers. If the bulk material trapped between abutting belt edges is allowed to accumulate between the adjacent edges, the sealing relationship between the belts may be lost and the bulk material may escape, particularly during a vertical portion of material transport. In addition, inadequate support for the transported material particularly during vertical transport can lead to separation of the belts and leakage of the material.
The present invention addresses the aforementioned limitations of the prior art by proving a tight seal between adjacent edges of a pair of bulk material transporting belts in the horizontal to vertical transition stage, as well as in the vertical transport of the bulk material. In the transition stage, either segmented belt edge guides or a pair of closely spaced, continuous tracks are used to maintain adjacent edges of the two moving endless belts in intimate contact. In the vertical stage of transport, plural spaced belt engaging mechanisms urge the two belts toward one another and support the transported material. The inventive vertical lift conveyor further includes an extendable intake stage which facilitates deposit of the bulk material onto the conveying belt, while reducing the “foot print” of the lift conveyor when not in use, or during transport.